The present invention relates to grafting of molecules onto nanoparticles. More specifically, the present invention relates to grafting of organic molecules onto Group IV nanoparticles.
Nanoparticles have recently attracted significant attention from researchers in a variety of disciplines, due to a wide array of potential applications in the fabrication of nanostructured materials and devices. Semiconductor nanoparticles, such as silicon nanoparticles, are of special interest due to their potential uses in photoluminescence-based devices, doped electroluminescent light emitters, photovoltaic devices, memory devices and other microelectronic devices, such as diodes and transistors.
In many instances, it is desirable to graft molecules onto the surface of nanoparticles. The grafting of molecules to the surface is sometimes called “passivation,” but may also impart new properties to the nanoparticles. In one example prior art approach to grafting molecules, nanoparticles are collected as a powder and then transferred into mixtures of solvents and ligands molecules and reacted for several minutes to hours. This process can be used to attach the ligands to the surface of the nanoparticles. The ligand molecules should have a sufficient length such that they are able to overcome the van der Walls forces between particles to push agglomerated nanoparticles apart. Another example prior art technique is the thermal gas phase method. In the thermal gas phase method, the molecules are electrically neutral and no charge prevents them from agglomerating. In order to passivate these particles while avoiding agglomeration, the thermal method is limited to relatively small particle concentrations such that the particles remain sufficiently separated and do not agglomerate.